diff --git a/src/interfaces/summary.interface.ts b/src/interfaces/summary.interface.ts
new file mode 100644
index 0000000..fa2a469
--- /dev/null
+++ b/src/interfaces/summary.interface.ts
@@ -0,0 +1,7 @@
+import { google } from "@google-cloud/language/build/protos/protos";
+
+export interface Summary {
+  wordFrequency: [string, number][];
+  replyToStatusId: string;
+  sentiment: google.cloud.language.v1.IAnalyzeSentimentResponse;
+}
diff --git a/src/outgoing.ts b/src/outgoing.ts
index f1214fd..17e16e9 100644
--- a/src/outgoing.ts
+++ b/src/outgoing.ts
@@ -1,16 +1,27 @@
+import { Summary } from "./interfaces/summary.interface";
 import { logger } from "./utility/logger";
 import { twitterClient } from "./utility/twitter/twitter-client";
 
-export async function sendAnswer(summary: any): Promise<void> {
+export async function sendAnswer(summary: Summary): Promise<void> {
   const client = twitterClient();
   const status = summary.wordFrequency
     .splice(0, 5)
-    .map((element: any) => element[0])
+    .map((element: [string, number]) => element[0])
     .join(", ");
+  if (summary.sentiment.documentSentiment === null) {
+    throw new Error("documentSentiment is null. ");
+  }
+  if (summary.sentiment.documentSentiment === undefined) {
+    throw new Error("documentSentiment is undefined. ");
+  }
   const sentimentScore = summary.sentiment.documentSentiment.score || 0;
-  const sentimentScoreRounded = Number.parseFloat(sentimentScore).toFixed(2);
+  const sentimentScoreRounded = Number.parseFloat(
+    String(sentimentScore)
+  ).toFixed(2);
   const magnitudeScore = summary.sentiment.documentSentiment.magnitude || 0;
-  const magnitudeScoreRounded = Number.parseFloat(magnitudeScore).toFixed(2);
+  const magnitudeScoreRounded = Number.parseFloat(
+    String(magnitudeScore)
+  ).toFixed(2);
   let sentimentScoreString = "Neutral";
   if (sentimentScore <= -0.25 && sentimentScore >= -1) {
     sentimentScoreString = "Negative";
diff --git a/src/utility/queue.ts b/src/utility/queue.ts
index 0d1d1b6..99f3d97 100644
--- a/src/utility/queue.ts
+++ b/src/utility/queue.ts
@@ -1,5 +1,6 @@
+import { Summary } from "../interfaces/summary.interface";
 import { Tweet } from "../interfaces/twitter/tweet.interface";
 
 export const queueQuestion: Tweet[] = [];
-export const queueSummary: any[] = [];
-export const queueReport: any[] = [];
+export const queueSummary: Summary[] = [];
+export const queueReport: unknown[] = [];
diff --git a/src/utility/twitter/tweet-utilities.ts b/src/utility/twitter/tweet-utilities.ts
index 6f37690..53f4e6d 100644
--- a/src/utility/twitter/tweet-utilities.ts
+++ b/src/utility/twitter/tweet-utilities.ts
@@ -1,5 +1,7 @@
 import sw from "stopword";
 import TextCleaner from "text-cleaner";
+import { Summary } from "../../interfaces/summary.interface";
+import { Tweet } from "../../interfaces/twitter/tweet.interface";
 import { WordFrequency } from "../../interfaces/word-frequency.interface";
 import { axiosClient } from "../axios-retry-configuration";
 import { analyseSentiment } from "../gcp/sentiment";
@@ -10,7 +12,9 @@ import { regexTwitterHandle, regexURL } from "../regex";
 const token = process.env.TWITTER_BEARER_TOKEN || "";
 const recentSearchURL = "https://api.twitter.com/2/tweets/search/recent";
 
-export async function recentSearch(username: string) {
+export async function recentSearch(
+  username: string
+): Promise<{ length: number; data: [] }> {
   // Edit query parameters below
   const parameters = {
     query: `from:${username} -is:retweet`,
@@ -30,17 +34,19 @@ export async function recentSearch(username: string) {
   return response.data;
 }
 
-export async function generateWordFrequency(words: string[]) {
+export async function generateWordFrequency(
+  words: string[]
+): Promise<[string, number][]> {
   if (words.length === 0) {
-    return;
+    throw new Error("The received words length is zero. ");
   }
   const wordFrequency: WordFrequency = {};
   words.forEach((element: string) => {
     // Keep track of occurences
     if (Object.prototype.hasOwnProperty.call(wordFrequency, element)) {
-      wordFrequency[element] += 1;
+      wordFrequency[String(element)] += 1;
     } else {
-      wordFrequency[element] = 1;
+      wordFrequency[String(element)] = 1;
     }
   });
 
@@ -53,13 +59,13 @@ export async function generateWordFrequency(words: string[]) {
   });
 }
 
-export async function generateWordsArray(tweets: any) {
-  if (tweets.length === 0) {
-    return;
-  }
+export async function generateWordsArray(tweets: {
+  length: number;
+  data: [];
+}): Promise<string[]> {
   let recentTweetsConcat = "";
   if (tweets["data"]) {
-    tweets["data"].forEach((element: any) => {
+    tweets["data"].forEach((element: { text: string }) => {
       if (element.text)
         recentTweetsConcat = recentTweetsConcat + " " + element.text;
     });
@@ -82,7 +88,9 @@ export async function generateWordsArray(tweets: any) {
   ]);
 }
 
-export async function generateSummary(question: any) {
+export async function generateSummary(
+  question: Tweet
+): Promise<Summary | void> {
   try {
     const recentTweets = await recentSearch(question.in_reply_to_user_id_str);
     const wordsArray = await generateWordsArray(recentTweets);